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The double-deficit hypothesis for the developmental dyslexia Journal of Educational Psychology

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Abstract

The authors propose an alternative conceptualization of the developmental dyslexias, the double-deficit hypothesis (i.e., phonological deficits and processes underlying naming-speed deficits represent 2 separable sources of reading dysfunction). Data from cross-sectional, longitudinal, and cross-linguistic studies are reviewed supporting the presence of 2 single-deficit subtypes with more limited reading impairments and 1 double-deficit subtype with more pervasive and severe impairments. Naming-speed and phonological-awareness variables contribute uniquely to different aspects of reading according to this conception, with a model of visual letter naming illustrating both the multicomponential nature of naming speed and why naming speed should not be subsumed under phonological processes. Two hypotheses concerning relationships between naming-speed processes and reading are considered. The implications of processing speed as a second core deficit in dyslexia are described for diagnosis and intervention. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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... The DDH (Bowers & Wolf, 1993;Wolf & Bowers, 1999) was developed as an extension of the dominant phonological account (Ziegler et al., 2019). The DDH acknowledges the phonological impairment as a core deficit in dyslexia but proposes that there is a second independent core deficit in processes indexed by NS. ...
... The DDH postulates that NS is an independent core deficit in developmental dyslexia that may underlie reading difficulties in addition to or in the absence of a phonological deficit. That is, PA and NS deficits are separable sources of reading difficulties, whereas their combined presence leads to even more severe reading impairment (Wolf & Bowers, 1999;Wolf et al., 2000). Children with a double deficit have been found most impaired in word identification, word decoding, and reading comprehension (Wolf et al., 2000), and also in reading fluency in different languages (Steacy et al., 2014;Torppa et al., 2013), compared to children with a single deficit. ...
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This study investigated the triple-deficit hypothesis in Arabic, a Semitic transparent orthography, among 258 native Arabic children from Grade 3, divided into a typical readers group (n = 204) and a dyslexia group (n = 54). Children were tested on word-and pseudoword-reading accuracy, word-reading fluency, phonological awareness (PA), naming speed (NS), orthographic processing (OP), and nonverbal reasoning ability. The results indicated that all children with dyslexia had either double or triple deficits, and none of them had a single deficit. Children with triple deficits showed lower performance than children with single and no deficits on all the reading measures. They have also lower performance to children with double deficits on word-reading accuracy but comparable scores in word-and pseudoword-reading fluency. In addition, OP was confirmed as an additional independent predictor of word-level reading skills besides PA and NS, while controlling for age and nonverbal intelligence. The classification findings showed that the presence of a triple deficit maximizes the risk of reading failure. These findings support the additive nature of combined deficits in PA, NS, and OP. Moreover, they establish the benefit of including OP as a third deficit, in addition to PA and NS, underlying dyslexia in Arabic.
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This study investigates the linguistic processing and non-linguistic cognitive abilities of monolingual and bilingual children with and without reading difficulties and examines the relationship between these skills and reading. There were 72 Italian-speaking children: 18 monolingual good readers (MONO-GR, Mage = 10;4), 19 monolingual poor readers (MONO-PR, Mage = 10;3), 21 bilingual good readers (BI-GR, Mage = 10;6), and 16 bilingual poor readers (BI-PR, Mage = 10;6). All bilingual children spoke Italian as their L2. Children completed a battery of standardized Italian reading tests, language-dependent tasks: nonword repetition (NWR), sentence repetition (SR), and phonological awareness (PA), and language-independent tasks: timing anticipation, beat synchronization, inhibition control, auditory reaction time, and rapid automatized naming (RAN). Poor readers scored below good readers on the language-dependent tasks, including NWR, PA, and SR. Beat synchronization was the only language-independent task sensitive to reading ability, with poor readers showing greater variability than good readers in tapping to fast rhythms. SR was the only task influenced by language experience as bilinguals underperformed monolinguals on the task. Moreover, there were weak to moderate correlations between performance on some language-dependent tasks (NWR, PA), language-independent tasks (inhibition control, RAN), and reading measures. Performance on the experimental tasks (except for RAN) was not associated with the length of exposure to Italian. The results highlight the potential of NWR, PA, SR, and beat synchronization tasks in identifying the risk of dyslexia in bilingual populations. Future research is needed to validate these findings and to establish the tasks’ diagnostic accuracy.
Article
The association between pre-reading skills and phonological production skills has been shown at school age, but less is known about how these skills interact at an earlier age when they are just developing. The focus was to investigate whether a connection between pre-reading skills (letter naming, rapid automatised naming; RAN) and phonological production skills of children at 3;6 could be found. In addition, the possible effects of the following skills were considered in the analysis: auditory word recognition and lexical ability at 3;6; and early expressive lexicon size at 2;0, adding a longitudinal aspect to the study. The participants were Finnish-speaking children (n = 66). The results show a significant connection between letter naming skills and phonological measures (paradigmatic and phonotactic skills) at 3;6, whereas no association was found between RAN and phonological production skills. Phonological production skills were significantly correlated with all the variables: pre-reading, lexical and auditory word recognition. The pre-reading measure correlated only with phonological production skills and lexical ability that was measured concurrently at 3;6. The findings propose a central role for the phonological production skill in terms of pre-reading skills, auditory word recognition and previous and concurrent lexical ability.
Chapter
One of the key topics for establishing meaningful links between brain sciences and education is the development of reading. How does biology constrain learning to read? How does experience shape the development of reading skills? How does research on biology and behaviour connect to the ways that schools, teachers and parents help children learn to read, particularly in the face of disabilities that interfere with learning? This book addresses these questions and illuminates why reading disorders have been hard to identify, how recent research has established a firm base of knowledge about the cognitive neuroscience of reading problems and the learning tools for overcoming them, and finally, what the future holds for relating mind, brain and education to understanding reading difficulties. Connecting knowledge from neuroscience, genetics, cognitive science, child development, neuropsychology and education, this book will be of interest to both academic researchers and graduate students.
Chapter
One of the key topics for establishing meaningful links between brain sciences and education is the development of reading. How does biology constrain learning to read? How does experience shape the development of reading skills? How does research on biology and behaviour connect to the ways that schools, teachers and parents help children learn to read, particularly in the face of disabilities that interfere with learning? This book addresses these questions and illuminates why reading disorders have been hard to identify, how recent research has established a firm base of knowledge about the cognitive neuroscience of reading problems and the learning tools for overcoming them, and finally, what the future holds for relating mind, brain and education to understanding reading difficulties. Connecting knowledge from neuroscience, genetics, cognitive science, child development, neuropsychology and education, this book will be of interest to both academic researchers and graduate students.
Chapter
One of the key topics for establishing meaningful links between brain sciences and education is the development of reading. How does biology constrain learning to read? How does experience shape the development of reading skills? How does research on biology and behaviour connect to the ways that schools, teachers and parents help children learn to read, particularly in the face of disabilities that interfere with learning? This book addresses these questions and illuminates why reading disorders have been hard to identify, how recent research has established a firm base of knowledge about the cognitive neuroscience of reading problems and the learning tools for overcoming them, and finally, what the future holds for relating mind, brain and education to understanding reading difficulties. Connecting knowledge from neuroscience, genetics, cognitive science, child development, neuropsychology and education, this book will be of interest to both academic researchers and graduate students.
Chapter
One of the key topics for establishing meaningful links between brain sciences and education is the development of reading. How does biology constrain learning to read? How does experience shape the development of reading skills? How does research on biology and behaviour connect to the ways that schools, teachers and parents help children learn to read, particularly in the face of disabilities that interfere with learning? This book addresses these questions and illuminates why reading disorders have been hard to identify, how recent research has established a firm base of knowledge about the cognitive neuroscience of reading problems and the learning tools for overcoming them, and finally, what the future holds for relating mind, brain and education to understanding reading difficulties. Connecting knowledge from neuroscience, genetics, cognitive science, child development, neuropsychology and education, this book will be of interest to both academic researchers and graduate students.
Chapter
One of the key topics for establishing meaningful links between brain sciences and education is the development of reading. How does biology constrain learning to read? How does experience shape the development of reading skills? How does research on biology and behaviour connect to the ways that schools, teachers and parents help children learn to read, particularly in the face of disabilities that interfere with learning? This book addresses these questions and illuminates why reading disorders have been hard to identify, how recent research has established a firm base of knowledge about the cognitive neuroscience of reading problems and the learning tools for overcoming them, and finally, what the future holds for relating mind, brain and education to understanding reading difficulties. Connecting knowledge from neuroscience, genetics, cognitive science, child development, neuropsychology and education, this book will be of interest to both academic researchers and graduate students.
Article
Childhood socioeconomic status (SES) strongly predicts disparities in reading development, yet it is unknown whether early environments also moderate the cognitive and neurobiological bases of reading disorders (RD) such as dyslexia, the most prevalent learning disability. SES-diverse 6-9-year-old children (n=155, half with RD) completed behavioral and functional magnetic resonance imaging (fMRI) tasks engaging phonological and orthographic processing, which revealed corresponding double-dissociations in neurocognitive deficits. At the higher end of the SES spectrum, RD was most strongly explained by differences in phonological skill and corresponding activation in left inferior frontal and temporoparietal regions during phonological processing—widely considered the “core deficit” of RD. However, at the lower end of the SES spectrum, RD was most strongly explained by differences in rapid naming skills and corresponding activation in left temporoparietal and fusiform regions during orthographic processing. Findings indicate that children’s early environments systematically moderate the neurocognitive systems underlying RD, which has implications for assessment and treatment approaches to reduce SES disparities in RD outcomes. Further, results suggest that reliance on high-SES convenience samples may mask critical heterogeneity in the foundations of both typical and disordered reading development.
Article
The relations between socioeconomic status (SES) and language skills at the onset of reading acquisition has not received much attention in research. In this study, a standardized battery of oral and written language tests was administered to 127 Arabic-speaking children at the end of first grade. SES-related differences were found in a line of oral language measures (vocabulary, syntax, morphology, and listening comprehension), but not in phonological awareness (PA) and rapid automatized naming (RAN), nor in any of the reading components (decoding, word reading, reading comprehension and orthographic knowledge). These findings point to a distinction between two groups of language skills with regard to their relations with SES in the first year of reading instruction. The results imply that SES should not be regarded as a mediating factor in the development of PA, RAN and reading in first grade among novice readers of Arabic.
Chapter
This chapter discusses the mechanisms underlying saccadic suppression in specifically disabled and normal readers. The research addressed in the chapter concerned with the mechanisms argued to be involved in saccadic suppression in a particular group of children who have trouble learning to read. Children in this group are commonly referred to as specifically reading disabled (SRD) and are defined as children of normal intelligence, with normal education opportunities, no brain damage, and no gross behavioral problems who nevertheless read at least two years behind the level expected for this age and intelligence. The data show that many SRDs have a particular visual deficit. It has also been shown that it is unlikely that the transient deficit results from being unable to read although it is not yet known how it may contribute to reading difficulties. This problem appears to be present in a large percentage of disabled readers and not just for a sub-group frequently referred to as visuo-spatial dyslexics. The results with different modes of visual presentation are further investigated in the laboratory and are encouraging.
Article
• Three phases comprise the development of word reading skill: accuracy, automaticity, and speed. The 3rd phase is reached when components of the identification process (i.e., graphic, phonological, semantic) are unitized in memory for particular words. Attainment of this final phase was explored with 2 experiments. In Exp I with Ss from 1st-, 2nd-, and 4th-grade classes, skilled and less skilled readers identified familiar printed words, CVC nonwords, digits, and pictures. Attainment of unitized speeds to printed words was inferred if Ss identified words as rapidly as digits. This level was exhibited by skilled readers in all grades but by less skilled readers only in 4th grade. Unitized speed with CVCs was evident among 2nd- and 4th-grade skilled readers, but not among less skilled readers at any grade. In Exp II, 18 1st-grade and 19 2nd-grade poor readers practiced reading familiar words and CVCs. Practice boosted RTs to CVCs but not to words read accurately before training, and RTs to both remained slower than digit RTs, indicating that practice promotes the development of unitized speeds very slowly in less skilled readers. (45 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved) • Three phases comprise the development of word reading skill: accuracy, automaticity, and speed. The 3rd phase is reached when components of the identification process (i.e., graphic, phonological, semantic) are unitized in memory for particular words. Attainment of this final phase was explored with 2 experiments. In Exp I with Ss from 1st-, 2nd-, and 4th-grade classes, skilled and less skilled readers identified familiar printed words, CVC nonwords, digits, and pictures. Attainment of unitized speeds to printed words was inferred if Ss identified words as rapidly as digits. This level was exhibited by skilled readers in all grades but by less skilled readers only in 4th grade. Unitized speed with CVCs was evident among 2nd- and 4th-grade skilled readers, but not among less skilled readers at any grade. In Exp II, 18 1st-grade and 19 2nd-grade poor readers practiced reading familiar words and CVCs. Practice boosted RTs to CVCs but not to words read accurately before training, and RTs to both remained slower than digit RTs, indicating that practice promotes the development of unitized speeds very slowly in less skilled readers. (45 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Chapter
Although most people learn to produce and understand spoken language without formal instruction, this is not the case in learning to read. Reading and writing is a method of communication which is man-made, and appeared relatively late in history. Because it is one of those activities which today’s society expects its citizens to master, it is a skill that is formally taught in schools.
Article
Three bodies of research that have developed in relative isolation center on each of three kinds of phonological processing: phonological awareness, awareness of the sound structure of language; phonological recoding in lexical access, recoding written symbols into a sound-based representational system to get from the written word to its lexical referent; and phonetic recoding in working memory, recoding written symbols into a sound-based representational system to maintain them efficiently in working memory. In this review we integrate these bodies of research and address the interdependent issues of the nature of phonological abilities and their causal roles in the acquisition of reading skills. Phonological ability seems to be general across tasks that purport to measure the three kinds of phonological processing, and this generality apparently is independent of general cognitive ability. However, the generality of phonological ability is not complete, and there is an empirical basis for distinguishing phonological awareness and phonetic recoding in working memory. Our review supports a causal role for phonological awareness in learning to read, and suggests the possibility of similar causal roles for phonological recoding in lexical access and phonetic recoding in working memory. Most researchers have neglected the probable causal role of learning to read in the development of phonological skills. It is no longer enough to ask whether phonological skills play a causal role in the acquisition of reading skills. The question now is which aspects of phonological processing (e.g., awareness, recoding in lexical access, recoding in working memory) are causally related to which aspects of reading (e.g., word recognition, word analysis, sentence comprehension), at which point in their codevelopment, and what are the directions of these causal relations?
Chapter
The title of this volume is The varieties of orthographic knowledge I: Theoretical and developmental issues. The authors have met this charge so well that the reader may be overwhelmed by the varieties of orthographic knowledge and despairing of any hope for consensus. Yet there are at least three points of consensus among the authors. First, in studying reading, phonological processing skill has been over-emphasized at the expense of orthographic processing skill. Second, orthographic processing can be operationalized and assessed separately from phonological processing. Third, although orthographic and phonological processing can be dissociated statistically, they are conceptually intertwined.
Article
In this experiment, we examined whether teaching beginners to produce phonetic spellings improves their ability to read words. Kindergarten students who could name letters but could not spell words with consonant clusters were assigned either to an experimental group that was taught to spell or to a control group that practiced matching letters to isolated sounds. According to posttest performances, spelling-trained subjects learned to read a set of words more effectively than controls. Their greater success was not because they had learned how to sound out and blend the words, but rather because they had become better at phonetic cue reading, which entails reading words by remembering associations between letters in spellings and sounds in pronunciations. Spelling training also improved phonetic segmentation and spelling recognition skills. Findings suggest the value of linking spelling instruction to reading instruction when children first begin learning to read. /// [French] Par cette expérience on a voulu vérifier si l'enseignement de l'orthographe phonétique aux débutants pouvait les aider à mieux lire les mots. On a choisi des élèves de maternelle connaissant déjà leurs lettres mais incapables d'épeler des mots contenant des consonnes adjacentes, qui ont ensuite été assignés soit à un groupe expérimental auquel on enseignait l'épellation, ou à un groupe contrôle soumis à des exercices de jumelage de lettres et de sons isolés. Selon les performances obtenues lors du posttest, les bénéficiaires de l'enseignement de l'épellation ont démontré de meilleures aptitudes que le groupe contrôle lors de la lecture d'une série de mots. On n'attribuait pas leurs meilleurs résultats au fait qu'ils aient appris à prononcer et à former les mots mais plutôt au fait qu'ils se soient améliorés au niveau du déchiffrage phonétique; ceci leur permettait de mieux lire les mots grâce au rappel des associations possibles entre les lettres à l'orthographe, et des sons à la prononciation. L'enseignement de l'épellation a aussi permis d'améliorer leurs capacités au niveau de la segmentation phonétique et de l'identification orthographique. Les résultats suggèrent l'importance d'associer l'apprentissage de l'orthographe à celui de la lecture quand les enfants commencent par la lecture. /// [Spanish] En este experimento se examinó si enseñar a los principiantes a producir deletreo fonético mejora su habilidad para leer palabras. Se asignaron alumnos de jardín de niños que podían nombrar las letras pero que no podían deletrear palabras con consonantes en grupo a dos grupos. Al grupo experimental se le enseñó a deletrear y al grupo control a practicar relacionar letras a sonidos aislados. De acuerdo a los post-tests de desempeño los estudiantes del grupo experimental que aprendieron a deletrear, pudieron leer un grupo de palabras de manera más efectiva que los del grupo control. La razón de su éxito no se debe a que aprendieron a "sonar" y mezclar las palabras, sino más bien a que se volvieron mejores para leer claves fonéticas, lo que implica leer palabras a través de recordar asociaciones entre letras escritas y sonidos en pronunciaciones. El entrenamiento en deletreo también mejoró la segmentación fonética y la habilidad de reconocimiento de deletreos. Los hallazgos apuntan al valor de ligar la instrucción de deletreo a la de lectura cuando los niños recién empiezan a leer. /// [German] In diesem experiment wurde untersucht, ob Anfängern phonetisches Buchstabieren beigebracht und dadurch ihre Lese-Fähigkeit gesteigert werden kann. Vorschüler, die Buchstaben nennen, jedoch Worte mit Konsonanten-Gruppen nicht buchstabieren konnten, wurden einer Experimentier-Gruppe zugeteilt, in welcher das Buchstabieren erlernt wurde, oder aber einer Kontroll-Gruppe, welche übte, Buchstaben auf vereinzelte Laute abzustimmen. Nach einer dem Test folgenden Aufgabe zu schließen, lernten die Schüler, die Buchstabieren geübt hatten, schneller Sätze zu formen als die der Kontroll-Gruppe. Der Erfolg war jedoch nicht darauß zurückzuführen, daß sie gelernt hatten, Worte herauszuhören und miteinander zu verbinden, sondern weil sich ihr phonitisches Stichwort-Wissen verbessert hatte, ein Vorgang, bei dem Worte gelernt werden, indem die Verbindung erkannt wird zwischen Buchstaben beim Buchstabieren und Lauten bei der Aussprache. Buchstabier-Uebungen verbesserten ebenfalls die phonetische Einteilung und Buchstaben-Erkenntnis. Die Resultate zeigen auf, daß es wichtig ist, Buchstabier-Uebungen mit dem Lese-Ueben zu verbinden, wenn Kinder das Lesen lernen.
Article
The authors assessed the effectiveness of two microcomputer programs for improving word recognition/decoding skills, and the extent to which decoding improvements lead to improvements in reading comprehension. The programs were used for 8 months in all three fourth-grade classes of a school with a history of low reading achievement, and whose students were from low socioeconomic backgrounds. Measures included standardized achievement tests and laboratory tasks. The authors found that use of the programs led (a) to substantial increases in word recognition/decoding skills, and (b) to substantial improvements in comprehension at the word and proposition/sentence level, but to no improvement at the passage level. The implications of these findings for theories of the relationship between decoding and comprehension are discussed. /// [French] Les auteurs évaluent l'efficacité de deux programmes micro-informatiques conçus pour améliorer la capacité d'identification/décodage des mots et veulent savoir jusqu'à quel point les progrès au niveau du décodage peuvent entraîner une meilleure compréhension en lecture. On a utilisé les programmes pendant huit mois avec les trois groupes de quatrième année d'une même école dont le passé démontre de faibles résultats en lecture et dont les élèves proviennent de familles défavorisées. Pour procéder à cette évaluation, on a utilisé des tests standardisés et des exercices de laboratoire. Selon les résultats obtenus, l'utilisation des programmes a entraîné (a) un progrès considérable au niveau de la capacité d'identification/décodage des mots, et (b) une importante amélioration de la compréhension au niveau de la phrase/proposition, mais aucune amélioration au niveau de la compréhension d'un passage. Les auteurs discutent de l'implication de ces résultats sur la validité de la théorie de l'efficacité verbale de Perfetti et Lesgold (1977, 1979). /// [Spanish] Los autores estiman la efectividad de dos programas para microcomputadoras para mejorar las habilidades de reconocimiento y decodificación de palabras, y la extensión a la que una mejora en la decodificación se traduce en mejora también en la comprensión de lectura. Los programas se usaron durante ocho meses en las tres clases de cuarto grado de una escuela que tenía una larga historia de bajo rendimiento en lectura, y cuyos estudiantes provenían de familias con un estatus socioeconómico bajo. Las medidas usadas incluían pruebas estandarizadas de rendimiento y tareas de laboratorio. De acuerdo a los resultados, el uso de los programas condujo (a) a incrementos substanciales en las habilidades de reconocimiento y decodificación de palabras y (b) a mejoras substanciales en comprensión al nivel de frases y proposiciones, aunque sin mejora alguna a nivel de pasaje. Los autores discuten las implicaciones de estos hallazgos en relación a la validez de la teoría de eficiencia verbal de Perfetti y Lesgold (1977, 1979). /// [German] Die autoren bewerten die Wirksamkeit von zwei Mikrokomputer-Programmen für die Verbesserung von Worterkenntnis/entzifferungsgeschick, und das Ausmaß, in dem Entzifferungsverbesserungen zu Verbesserungen im Leseverständnis führen. Diese Programme wurden angewandt in einer Acht-Monats-Spanne in allen drei der Viertschuljahr-Klassen einer Schule, die den Ruf hat, Schüler aufzuweisen, die aus Familien mit niedrigem sozialwirtschaftlichem Stand stammen und geringe Lesefähigkeiten aufweisen. Die Maßnahmen enthielten, Standard-Fähigkeitsprüfugen sowie Labor-Aufgaben. Wie die Resultate zeigen, führte die Anwendung dieser Programme zu a) wesentlichen Erhöhungen der Worterkenntnis/entzifferungsfähigkeit und b) wesentlichen Verbesserungen im Verständnis von Präposition/Satz, jedoch keiner Verbesserung auf der Abschnittsebene. Die Autoren erörtern die Begleiterscheinungen dieser Resultate mit Sicht auf die Gültigkeit von Perfetti und Lesgolds (1977, 1979) Verbal-Leistungstheorie.